1. Field of the Invention
This invention relates to overhead line marker spheres and to a method of installing such markers on overhead lines.
2. Related Art
Various types of prior art aerial warning marker devices have been previously disclosed.
Williams, U.S. Pat. No. 3,253,571, discloses a helically wound device that can have a plurality of elongated shapes. The device is comprised of a series of coils that are simply rotated on to an aerial line.
Pfeiffer, U.S. Pat. No. 3,135,236, discloses a conically shaped device that is attached to a cable or aerial line by means of a clamp with a spring extending between the hanging on the spring beneath the cable.
Ruhlmen et al, U.S. Pat. No. 3,183,883, discloses a series of spherical segments that include trailing preformed helical wire portions that can be wrapped around a wire. By putting a plurality of these together, a geometrically shaped body can be formed that does not require clamping.
Many of the spherical type devices have required clamps at each end to clamp the sphere halves on to the cable. Such markers are shown in French Patent 1284766, Swiss Patent 579838 and Lematta, U.S. Pat. No. 3,430,325.
Hill et al, U.S. Pat. No. 3,362,377, shows a spring actuated hollow spherical body that is held open an when a pin is released closes about a high power line or other type of overhead cable. The two spherical segments are pivoted together at opposite ends and an opening is provided adjacent that pivoted connection, with the opening being filled with a resilient rubber material allowing the segments to clamp themselves to the line without cutting the line.
In Anderson et al, U.S. Pat. No. 4,474,133, a spherically shaped marker is hung by means of a clamp assembly, with the clamp itself being connected to the overhead cable.
In Osgood, U.S. Pat. No. 4,885,835, a spherical marker is disclosed that includes a peripheral flange. Half of the flange is bolted together and because the marker is made from a flexible material the other half of the radial flange can be flexed to an open position allowing the line to be slid through the opening. Bolts are then used to close the portion of the flange that had been opened. In order to hold the marker in place on the line, anchor wires extend from each end of the marker with these wires being twisted spirally around the line to thus hold the marker in position.